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1.
Front Immunol ; 13: 917014, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35812432

RESUMO

Among the most common types of brain tumor, gliomas are the most aggressive and have the poorest prognosis. Dolichyl-diphosphooligosaccharide protein glycosyltransferase non-catalytic subunit (DDOST) encodes a component of the oligosaccharide transferase complex and is related to the N-glycosylation of proteins. The role of DDOST in gliomas, however, is not yet known. First, we performed a pan cancer analysis of DDOST in the TCGA cohort. The expression of DDOST was compared between glioma and normal brain tissues in the GEO and Chinese Glioma Genome Atlas (CGGA) databases. In order to explore the role of DDOST in glioma, we analyze the impact of DDOST on the prognosis of glioma patients, with the CGGA 325 dataset as a test set and the CGGA 693 dataset as a validation set. Immunohistochemistry was performed on tissue microarrays to examine whether DDOST has an impact on glioma patient survival. Next, using single-cell sequencing analysis, GSEA, immune infiltration analysis, and mutation analysis, we explored how DDOST affected the glioma tumor microenvironment. Finally, we evaluated the clinical significance of DDOST for glioma treatment by constructing nomograms and decision curve analysis (DCA) curves. We found that DDOST was overexpressed in patients with high grade, IDH wild type, 1p19q non-codel and MGMT un-methylated, which was associated with poor prognosis. Patients with high levels of DDOST, regardless of their clinical characteristics, had a worse prognosis. Immunohistochemical analysis confirmed the results of the above bioinformatics analysis. Mechanistic analysis revealed that DDOST was closely associated with the glioma microenvironment and negatively related to tumor-infiltrating B cells and CD4+ T cells and positively related to CAFs and tumor-associated macrophages. In conclusion, these findings suggested that DDOST mediated the immunosuppressive microenvironment of gliomas and could be an important biomarker in diagnosing and treating gliomas.


Assuntos
Neoplasias Encefálicas , Glioma , Neoplasias Encefálicas/patologia , Glioma/patologia , Humanos , Imuno-Histoquímica , Prognóstico , Microambiente Tumoral
2.
Biomed Res Int ; 2022: 9305190, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35669721

RESUMO

Objectives: To investigate the risk factors of total blood loss (TBL) and hidden blood loss (HBL) in adolescent idiopathic scoliosis (AIS) patients undergoing posterior orthopedic surgery. Methods: The AIS patients who visited department of spine surgery between January 2015 and December 2020 were retrospectively reviewed. Those with a history of posterior orthopedic surgery for AIS were identified, and their clinical data were collected. Gross formula was used to calculate the TBL and HBL. SPSS 20.0 was used for statistical analysis. The potential risk factors of TBL and HBL were assessed by independent t-test or univariate analysis. The risk factors of TBL and HBL were determined by multiple linear regression. Results: A total of 114 patients were included in this study. Operative time (P < 0.001), postoperative platelets (PLT) (P = 0.001), the number of surgical fixation segments (P < 0.001), implanted screws (P < 0.001), hospital stay (P = 0.006), type of scoliosis (P < 0.001), and correction angle of scoliosis (P = 0.063) were the potential risk factors of TBL. Operative time (P < 0.000), postoperative PLT (P = 0.095), the number of surgical fixation segments (P < 0.001), implanted screws (P < 0.001), type of scoliosis (P < 0.001), correction angle of scoliosis (P = 0.073), and total blood volume (P = 0.098) were the potential risk factors of HBL. Multiple linear regression analysis showed that operative time (P = 0.003) and the number of surgical fixation segments (P = 0.014) were risk factors of TBL, while the number of surgical fixation segments (P = 0.004) was a risk factor of HBL. Conclusions: In AIS patients undergoing posterior internal fixation surgery, the operative time and the number of surgical fixation segments are risk factors of TBL, and the number of surgical fixation segments is a risk factor of HBL. Surgeons need to consider these factors when making surgical strategies for AIS patients.


Assuntos
Cifose , Escoliose , Fusão Vertebral , Adolescente , Perda Sanguínea Cirúrgica , Humanos , Estudos Retrospectivos , Fatores de Risco , Escoliose/cirurgia , Fusão Vertebral/efeitos adversos
3.
Pain Res Manag ; 2022: 3330260, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35685675

RESUMO

Objectives: To investigate the correlation between tamoxifen (TAM) and lumbar intervertebral disc (IVD) degeneration (IVDD). Methods: The patients who visited the department of spine surgery from January 2015 to December 2020 were retrospectively reviewed. Those with a history of breast cancer surgery were identified and their data were collected. These data included patients' age, body mass index (BMI), menstrual history, postoperative history, drug treatment plan, and imaging data. The participants were divided into the TAM group and the non-TAM group. Lumbar IVDD was assessed by lumbar lordosis (LL), vertebral CT density, lumbar disc height index (DHI), Modic changes, and modified Pfirrmann grading score. SPSS 20 was used for statistical analysis. Results: A total of 75 patients were included in this study, 46 patients in the TAM group and 29 patients in the non-TAM group. No significant differences were present in age, BMI, postoperative history, LL, and vertebral CT density between the two groups. The DHI of L1/2 and L2/3 in the TAM group was lower compared to the non-TAM group (P=0.038 and P=0.034, respectively), while comparisons regarding the DHI of L3/4, L4/5, and L5/S1, and the average DHI between TAM and non-TAM groups were not significant. The modified Pfirrmann grading scores of the L1/2 and L2/3 IVDs in the TAM group were higher than those in the non-TAM group (P=0.004 and P=0.025, respectively). Comparisons of L3/4, L4/5, and L5/S1 between the two groups were not significant. The comparisons regarding the occurrence of Modic changes did not show a significant difference between the TAM and non-TAM groups. Conclusions: This study indicates that there might be some positive correlation between TAM use and lumbar IVDD. In particular, the degeneration of L1/2 and L2/3 has shown a correlation with TAM use.


Assuntos
Degeneração do Disco Intervertebral , Estudos de Casos e Controles , Humanos , Degeneração do Disco Intervertebral/diagnóstico por imagem , Vértebras Lombares/diagnóstico por imagem , Vértebras Lombares/cirurgia , Estudos Retrospectivos , Tamoxifeno/efeitos adversos
4.
Eur Spine J ; 31(7): 1897-1905, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-35596799

RESUMO

PURPOSE: It has not been determined which factors were related to multilevel lumbar disc degeneration (MLDD). The objective of this study was to determine the prevalence of MLDD among symptomatic patients using the magnetic resonance imaging method. The study also aimed to clarify the associations between MLDD and suspected risk factors through a multivariate model. METHODS: A total of 530 young and middle-aged patients, suffered from low back pain were retrospectively assessed by 2 independent observers, who used sagittal T2-weighted MR imaging. Subjects were divided into two groups, MLDD group and non-MLDD group, according to the number of degenerated discs. Demographic and radiological data included age, gender, weight, height, body mass index, smoking status, alcohol drinking, lumbar lordosis, presence of hypertension (HT), diabetes mellitus and anemia. RESULTS: There were 309 men and 221 women with an average age of 37.5 ± 8.5 years. In general, 37.7% of patients were diagnosed with disc degeneration (DD) at more than two levels. Triple level DD was the most common pattern and was more prevalent in women (p <0.05). Using multivariate analyses, age (odds ratio [OR]: 1.14; 95% confidence interval [CI] 1.11-1.18; p <0.001), hypertension (OR: 2.67; 95% CI 1.38-5.16; p = 0.03) and anemia (OR: 3.84; 95% CI 2.03-7.28; p <0.001) were significantly associated with MLDD. CONCLUSION: Despite the young age of this cohort, MLDD is common among patients with low back pain. A significant independent association exists between age, HT, anemia and multilevel disc degeneration in the lumbar region.


Assuntos
Anemia , Hipertensão , Degeneração do Disco Intervertebral , Dor Lombar , Adulto , Anemia/complicações , Anemia/patologia , Feminino , Humanos , Degeneração do Disco Intervertebral/complicações , Degeneração do Disco Intervertebral/diagnóstico por imagem , Degeneração do Disco Intervertebral/epidemiologia , Dor Lombar/diagnóstico por imagem , Dor Lombar/epidemiologia , Vértebras Lombares/patologia , Imageamento por Ressonância Magnética/métodos , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos
5.
Front Immunol ; 12: 801985, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34966392

RESUMO

Ischemic stroke is caused by insufficient cerebrovascular blood and oxygen supply. It is a major contributor to death or disability worldwide and has become a heavy societal and clinical burden. To date, effective treatments for ischemic stroke are limited, and innovative therapeutic methods are urgently needed. Hypoxia inducible factor-1α (HIF-1α) is a sensitive regulator of oxygen homeostasis, and its expression is rapidly induced after hypoxia/ischemia. It plays an extensive role in the pathophysiology of stroke, including neuronal survival, neuroinflammation, angiogenesis, glucose metabolism, and blood brain barrier regulation. In addition, the spatiotemporal expression profile of HIF-1α in the brain shifts with the progression of ischemic stroke; this has led to contradictory findings regarding its function in previous studies. Therefore, unveiling the Janus face of HIF-1α and its target genes in different type of cells and exploring the role of HIF-1α in inflammatory responses after ischemia is of great importance for revealing the pathogenesis and identifying new therapeutic targets for ischemic stroke. Herein, we provide a succinct overview of the current approaches targeting HIF-1α and summarize novel findings concerning HIF-1α regulation in different types of cells within neurovascular units, including neurons, endothelial cells, astrocytes, and microglia, during the different stages of ischemic stroke. The current representative translational approaches focused on neuroprotection by targeting HIF-1α are also discussed.


Assuntos
Encéfalo/metabolismo , Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , AVC Isquêmico/metabolismo , Animais , Humanos
6.
Front Immunol ; 12: 707972, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34335623

RESUMO

Ischemic stroke, caused by a sudden disruption of blood flow to the brain, is a leading cause of death and exerts a heavy burden on both patients and public health systems. Currently available treatments for ischemic stroke are very limited and are not feasible in many patients due to strict time windows required for their administration. Thus, novel treatment strategies are keenly required. T cells, which are part of the adaptive immune system, have gained more attention for its effects in ischemic stroke. Both preclinical and clinical studies have revealed the conflicting roles for T cells in post-stroke inflammation and as potential therapeutic targets. This review summarizes the mediators of T cell recruitment, as well as the temporal course of its infiltration through the blood-brain-barrier, choroid plexus, and meningeal pathways. Furthermore, we describe the mechanisms behind the deleterious and beneficial effects of T cells in the brain, in both antigen-dependent and antigen-independent manners, and finally we specifically focus on clinical and preclinical studies that have investigated T cells as potential therapeutic targets for ischemic stroke.


Assuntos
AVC Isquêmico/imunologia , Linfócitos T/imunologia , Animais , Humanos , Inflamação/imunologia
7.
Proteomics ; 21(16): e2100035, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-34132035

RESUMO

Arsenic pollution impacts health of millions of people in the world. Inorganic arsenic is a carcinogenic agent in skin and lung cancers. The stem-loop binding protein (SLBP) binds to the stem-loop of the canonical histone mRNA and regulates its metabolism during cell cycle. Our previous work has shown arsenic induces ubiquitin-proteasome dependent degradation of SLBP and contributes to lung cancer. In this study, we established the first comprehensive SLBP interaction network by affinity purification-mass spectrometry (AP-MS) analysis, and further demonstrated arsenic enhanced the association between SLBP and a crucial chaperone complex containing heat shock proteins (HSPs) and ERp44. Strikingly, knockdown of these proteins markedly rescued the protein level of SLBP under arsenic exposure conditions, and abolished the increasing migration capacity of BEAS-2B cells induced by arsenic. Taken together, our study provides a potential new mechanism that a chaperone complex containing HSPs and ERp44 attenuates the stability of SLBP under both normal and arsenic exposure conditions, which could be essential for arsenic-induced high cell migration.


Assuntos
Arsênio , Arsênio/toxicidade , Proteínas de Choque Térmico , Humanos , Proteínas de Membrana , Chaperonas Moleculares , Proteínas Nucleares/metabolismo , Ligação Proteica , Estabilidade Proteica , Proteômica , Fatores de Poliadenilação e Clivagem de mRNA
8.
ACS Appl Mater Interfaces ; 12(49): 54694-54702, 2020 Dec 09.
Artigo em Inglês | MEDLINE | ID: mdl-33216521

RESUMO

The employment of hybrid perovskite MAPbX3 (MA = CH3NH3+, X = Br or I) as photocatalysts in a photocatalytic hydrogen evolution reaction represents a promising approach to store solar energy. However, the toxicity of Pb makes these materials difficult to pass environmental evaluation while the intrinsic moisture sensitivity puts forward high anhydrous requirements in photocatalysts synthesis, storage, and application, which further reduces their service life. Herein, we demonstrate a hydrogen-bond-free strategy to synthesize moisture-stable hypotoxic hybrid perovskite for photocatalytic application by replacing traditional protonated countercations with alkylated countercations in a Pb-free hybrid system, which prevents water eroding hybrid perovskites via strong hydrogen bonds. A zero-dimensional Bi-based perovskite (3-ethylbenzo[d]thiazol-3-ium)4Bi2I10 (EtbtBi2I10) was synthesized, which contains dimeric (Bi2I10)4- formed by edge-sharing (BiI6) octahedra being different from the binuclear cluster in widely studied MA3Bi2I9. Theoretical calculations indicate that the electron communication between inorganic and organic moieties is responsible for its broadband absorption with a narrow band gap of 2.04 eV. EtbtBi2I10 exhibits excellent stability in distilled water, moisture air, acid solution, and UV-light irradiation. It shows effective photocatalytic performance in HI splitting to generate hydrogen with the performance comparable with MAPbI3. Introducing electron and hole-transporting channels drastically enhances the photocatalytic reaction.

9.
IEEE Trans Biomed Eng ; 67(11): 3203-3210, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-32191878

RESUMO

OBJECTIVE: To investigate chronic durability of transparent graphene electrodes fabricated on polyethylene terephthalate (PET) and SU-8 substrates for chronic in vivo studies. METHODS: We perform systematic accelerated aging tests to understand the chronic reliability and failure modes of transparent graphene microelectrode arrays built on PET and SU-8 substrates. We employ graphene microelectrodes fabricated on PET substrate in chronic in vivo experiments with transgenic mice. RESULTS: Our results show that graphene microelectrodes fabricated on PET substrate work reliably after 30 days accelerated aging test performed at 87 °C, equivalent to 960 days in vivo lifetime. We demonstrate stable chronic recordings of cortical potentials in multimodal imaging/recording experiments using transparent graphene microelectrodes fabricated on PET substrate. On the other hand, graphene microelectrode arrays built on SU-8 substrate exhibit extensive crack formation across microelectrode sites and wires after one to two weeks, resulting in total failure of recording capability for chronic studies. CONCLUSION: PET shows superior reliability as a substrate for graphene microelectrode arrays for chronic in vivo experiments. SIGNIFICANCE: Graphene is a unique neural interface material enabling cross-talk free integration of electrical and optical recording and stimulation techniques in the same experiment. To date, graphene-based microelectrode arrays have been demonstrated in various multi-modal acute experiments involving electrophysiological sensing or stimulation, optical imaging and optogenetics stimulation. Understanding chronic reliability of graphene-based transparent interfaces is very important to expand the use of this technology for long-term behavioral studies with animal models.


Assuntos
Grafite , Animais , Eletrodos Implantados , Camundongos , Microeletrodos , Optogenética , Reprodutibilidade dos Testes
10.
J Proteome Res ; 19(4): 1788-1799, 2020 04 03.
Artigo em Inglês | MEDLINE | ID: mdl-32105074

RESUMO

Phosphorylation is crucial in regulating various biological processes. However, comprehensive phosphoproteomic profiling in the termination of liver regeneration (LR) is still missing. Here, we used Tandem Mass Tag (TMT) labeling coupled with phosphopeptide enrichment and two-dimensional (2D) liquid chromatography-mass spectrometry (LC-MS)/MS analysis to establish a global phosphoproteomic map in the liver of mice at day 5 after partial hepatectomy (PH). Altogether, 9731 phosphosites from 3443 proteins were identified and 7802 phosphosites from 2980 proteins were quantified. Motif analysis of the identified phosphosites revealed a diverse array of consensus sequences, suggesting that multiple kinase families including ERK/MAPK, PKA/PKC, CaMK-II, CKII, and CDK may be involved in the termination of LR. Functional clustering analysis of proteins with dysregulated phosphosites showed that they mainly participate in metabolic pathways, DNA replication, and tight junction. More importantly, the deletion of PP2Acα in the liver remarkably changes the overall phosphorylation profile, indicating its critical role in regulating the termination of LR. Finally, several differentially phosphorylated sites were validated by co-immunoprecipitation and Western blot. Taken together, our data unravel the first comprehensive phosphoproteomic map in the termination of LR in mice, which greatly expands our knowledge in the complicated regulation of this process and provides new directions for the treatment of liver cancer using liver resection.


Assuntos
Regeneração Hepática , Proteômica , Animais , Cromatografia Líquida , Fígado/metabolismo , Camundongos , Fosfoproteínas/genética , Fosfoproteínas/metabolismo , Fosforilação
11.
J Proteome Res ; 19(3): 1119-1130, 2020 03 06.
Artigo em Inglês | MEDLINE | ID: mdl-31950832

RESUMO

The COP9 signalosome (CSN) is an evolutionarily conserved multisubunit protein complex, which controls protein degradation through deneddylation and inactivation of cullin-RING ubiquitin E3 ligases (CRLs). Recently, the CSN complex has been linked to the NF-κB signaling pathway due to its association with the IKK complex. However, how the CSN complex is regulated in this signaling pathway remains unclear. Here, we have carried out biochemical experiments and confirmed the interaction between the CSN and IKK complexes. In addition, we have determined that overexpression of IKKα or IKKß leads to enhanced phosphorylation of CSN5, the catalytic subunit for CSN deneddylase activity. Mutational analyses have revealed that phosphorylation at serine 201 and threonine 205 of CSN5 impairs CSN-mediated deneddylation activity in vitro. Interestingly, TNF-α treatment not only enhances the interaction between CSN and IKK but also induces an IKK-dependent phosphorylation of CSN5 at serine 201, linking CSN to TNF-α signaling through IKK. Moreover, TNF-α treatment affects the CSN interaction network globally, especially the associations of CSN with the proteasome complex, eukaryotic translation initiation factor complex, and CRL components. Collectively, our results provide new insights into IKK-mediated regulation of CSN associated with the NF-κB signaling pathway.


Assuntos
NF-kappa B , Transdução de Sinais , Complexo do Signalossomo COP9/genética , Complexo do Signalossomo COP9/metabolismo , NF-kappa B/genética , NF-kappa B/metabolismo , Peptídeo Hidrolases/genética , Peptídeo Hidrolases/metabolismo , Fosforilação
12.
ACS Appl Mater Interfaces ; 11(40): 37256-37262, 2019 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-31496216

RESUMO

Facet engineering of anatase TiO2 by controlling the {001} exposure ratio has been the focus of numerous investigations to optimize photocatalytic activity. In particular, an introduction of fluoride ions during the crystal growth has been demonstrated to be very effective and decisive in realizing the facet exposure of the crystals. However, a key role of fluoride ions in stabilizing {001} exposure and improving subsequent photocatalytic activity of anatase TiO2 remains unclear up to date. Herein, a controlled thickness of anatase TiO2 nanosheets has been realized by introducing different amounts of ethanol into a HF acid-assisted hydrothermal reaction. The thinnest nanosheets with a thickness of ∼2.9 nm were evaluated to have the highest H2 production rate of 41.04 mmol·h-1·g-1 under ultraviolet light irradiation, and the corresponding quantum efficiency was determined to be 41.6% (λ = 365 nm). Moreover, it is proved for the first time that fluoride ions are bonded with Ti vacancies on {001} facets, and such defects are crucial for stabilizing the ultrathin nanosheets and improving their electron-hole separation, therefore leading to a highly efficient photocatalytic activity. The findings offer an opportunity to engineer facets and functionality of anatase TiO2 by controlling surface defects.

13.
J Orthop Surg Res ; 14(1): 94, 2019 Apr 04.
Artigo em Inglês | MEDLINE | ID: mdl-30947714

RESUMO

OBJECTIVES: The aim of this study was to explore the prevalence and risk factors for axial neck pain in patients undergoing multilevel anterior cervical decompression with fusion surgery. METHODS: In this study, 88 patients, who underwent multilevel anterior cervical decompression with fusion surgery from January 2012 to January 2017, were retrospectively reviewed. Based on the postoperative axial neck pain, the patients were classified into two groups: axial pain group and no axial pain group. The patients were followed up 3 weeks, 3 months, and 1 year after cervical anterior surgery for the early- and long-term clinical evaluation. The possible effect factors included demographic variables (age, sex, BMI, smoking, drinking, heart disease, hypertension, diabetes, preoperative kyphosis, preoperative axial neck pain, preoperative JOA scores, and ODI) and surgery-related variables (surgical option, vertebral lesions, spinal canal stenosis rate, superior fusion segment, presence of intramedullary high signal intensity). RESULTS: The prevalence of axial neck pain was 27.3% (24 cases of 88). Our results showed that preoperative axial neck pain (62% vs 23%, P < 0.001) and preoperative kyphosis (42% vs 21.9%, P < 0.001) were risk factors for axial pain after multilevel anterior cervical surgery. Additionally, for patients with preoperative cervical kyphosis, compared to no axial pain group, the axial neck group was significantly more likely to exist a higher preoperative angle of C2-7 (13.31 ± 2.33 vs 7.33 ± 2.56, P < 0.001) and a higher correction range for kyphosis (20.24 ± 4.12 vs 12.34 ± 3.12, P < 0.001). However, for all the patients with postoperative axial symptoms, the improvement rate of axial pain was significantly higher for patients without cervical kyphosis at the early-term follow-up (3 weeks) (P = 0.032), no significant differences were found at the medium-term (P = 0.554) and long-term follow-up (P = 0.902), and improvements of clinical symptom have no obvious difference at the last follow-up. CONCLUSIONS: Overall, preoperative axial neck pain and kyphosis could predict axial neck pain for patients undergoing multilevel anterior cervical decompression with fusion surgery, and recovery of cervical kyphosis may contribute to the long-term recovery of neural function, but may also suffer from risk of short-term axial pain, which could be reduced through moderate cervical curvature recovery.


Assuntos
Vértebras Cervicais/cirurgia , Descompressão Cirúrgica/efeitos adversos , Cervicalgia/etiologia , Dor Pós-Operatória/etiologia , Fusão Vertebral/efeitos adversos , Idoso , Vértebras Cervicais/diagnóstico por imagem , Descompressão Cirúrgica/métodos , Feminino , Seguimentos , Humanos , Cifose/complicações , Masculino , Pessoa de Meia-Idade , Cervicalgia/diagnóstico por imagem , Medição da Dor/métodos , Dor Pós-Operatória/diagnóstico por imagem , Radiografia , Estudos Retrospectivos , Fatores de Risco , Fusão Vertebral/métodos , Estenose Espinal/diagnóstico por imagem , Estenose Espinal/cirurgia
14.
Nat Commun ; 9(1): 1638, 2018 04 24.
Artigo em Inglês | MEDLINE | ID: mdl-29692407

RESUMO

For many decades, zero thermal expansion materials have been the focus of numerous investigations because of their intriguing physical properties and potential applications in high-precision instruments. Different strategies, such as composites, solid solution and doping, have been developed as promising approaches to obtain zero thermal expansion materials. However, microstructure controlled zero thermal expansion behavior via interface or surface has not been realized. Here we report the observation of an impressive zero thermal expansion (volumetric thermal expansion coefficient, -1.41 × 10-6 K-1, 293-623 K) in single-crystal ferroelectric PbTiO3 fibers with large-scale faceted and enclosed mesopores. The zero thermal expansion behavior is attributed to a synergetic effect of positive thermal expansion near the mesopores due to the oxygen-based polarization screening and negative thermal expansion from an intrinsic ferroelectricity. Our results show that a fascinating surface construction in negative thermal expansion ferroelectric materials could be a promising strategy to realize zero thermal expansion.

15.
Dalton Trans ; 47(7): 2306-2317, 2018 Feb 13.
Artigo em Inglês | MEDLINE | ID: mdl-29367993

RESUMO

Although great progress has been made in hybrid iodocuprates(i) as lighting phosphors, the effects of aromatic and aliphatic structure directing agents (SDAs) on their water stability, structure and photoluminescence (PL) properties are still not clear. Herein, aromatic N-heterocyclic 1,2-di(4-pyridyl)ethylene (dpe), aliphatic N-heterocyclic 1,8-diazabicyclo[5.4.0]undec-7-ene (dbu) and N-aminoethylpiperazine (app) were selected to be SDAs to construct two types of hybrid iodocuprates(i) via a facile in situ approach. Aromatic dpe-derived cations are successfully directed to form (Me2dpe)(CuI3) (1), (Me2dpe)n(Cu4I6)n (2), (Et2dpe)2(Cu6I10) (3), and (H2dpe)n(Cu2I4)n (4). Three of them contain unprecedented inorganic iodocuprate clusters or chains. The aliphatic N-heterocyclic dbu- and app-derivative cations are responsible for the formation of (Hdbu)n(Cu2I3)n (5) and (H3app)2(Cu2I6)·2I·2H2O (6), which contain a (Cu2I3)- chain and a (Cu2I6)4- binuclear cluster, respectively. For the first time, the influence mechanisms of the water stabilities of iodocuprate-based PL materials were disclosed, by analyzing the possible interactions between SDAs and water molecules. 1-2 are PL silent due to their "self-quenching effect". 3, 4 and5 exhibit bright red, orange and yellow solid-state PL emissions at room temperature respectively, originating from the charge transfer between inorganic iodocuprate species and organic N-heterocycles. The co-template approach leads to multiple charge transfers in 6, which features a tunable PL behavior from bluish green to white by varying the excitation light, and has a quantum yield up to 43% (the highest value among hybrid iodocuprates containing (Cu2I6)4- clusters). The comparative study not only helps us to rationally synthesize iodocuprate-based PL materials with enhanced performance, but also provides a new method to obtain wavelength-dependent PL materials.

16.
ACS Appl Mater Interfaces ; 10(6): 5785-5792, 2018 Feb 14.
Artigo em Inglês | MEDLINE | ID: mdl-29368504

RESUMO

Freestanding and single-crystal BiFeO3 (BFO) nanoplates have been successfully synthesized by a fluoride ion-assisted hydrothermal method, and the thickness of the nanoplates can be effectively tailored from 80 to 380 nm by the concentration of fluoride ions. It is revealed that BFO nanoplates grew via an oriented attachment of layer by layer, giving rise to the formation of the inner interface within the nanoplates. In particular, antiferromagnetic (AFM) phase-transition temperature (Néel temperature, TN) of the BFO nanoplates is significantly enhanced from typical 370 to ∼512 °C, whereas the Curie temperature (TC) of the BFO nanoplates is determined to be ∼830 °C, in good agreement with a bulk value. The combination of scanning transmission electron microscopy, electron energy loss spectroscopy, and the first-principle calculations reveals that the interfacial tensile strain remarkably improves the stability of AFM ordering, accounting for the significant enhancement in TN of BFO plates. Correspondingly, the tensile strain induced the polarization and oxygen octahedral tilting has been observed near the interface. The findings presented here suggest that single-crystal BFO nanoplate is an ideal system for exploring an intrinsic magnetoelectric property, where a tensile strain can be a very promising approach to tailor AFM ordering and polarization rotation for an enhanced coupling effect.

17.
Dalton Trans ; 46(37): 12474-12486, 2017 Sep 26.
Artigo em Inglês | MEDLINE | ID: mdl-28894867

RESUMO

Two types of in situ formed structure directing agents (SDAs) including aromatic triphenylphosphine (PPh3)- and aliphatic piperazine (H2pp)-derivative cations were used to synthesize five new hybrid iodoargentates, namely (EtPPh3)Ag3I4 (1, Et = ethyl), (n-PrPPh3)Ag3I4 (2, n-Pr = n-propyl), (i-PrPPh3)Ag5I6 (3, i-Pr = isopropyl), (Me4pp)0.5AgI2 (4, Me = methyl), and (H3app)2(Ag2I6)·2I·2H2O (5, app = N-aminoethylpiperazine). A comparative study of the two types of SDAs on the structures, stabilities and properties of hybrid iodoargentates was performed in detail. Structurally, except for (EtPPh3)+ and (n-PrPPh3)+, which both directly form (Ag3I4)- anionic chains in 1 and 2, three SDAs generate hybrid iodoargentates different from each other with inorganic anions ranging from a 0-D (Ag2I6)4- dimer to 1-D α-type (AgI2)- and (Ag5I6)- chains. With regard to the electronic structures, aromatic PPh3-derivative cations make noticeable contributions to the bottom of the conduction bands, while aliphatic pp-derivative cations make nearly no contribution to the frontier orbitals, clearly indicating their different ways to adjust the band gaps. With regard to stability, the decomposition temperatures of 1-3 in the range of 324-349 °C are noticeably higher than the values of 217 and 225 °C for 4 and 5. Furthermore, 1-4 exhibit good water stabilities, which is ascribed to the alkylation reactions precluding the formation of strong hydrogen bonds between alkylated SDAs and extraneous H2O molecules. Contrarily, the presence of typical hydrophilic [double bond, length as m-dash]NH2+, [triple bond, length as m-dash]NH+ and -NH3+ groups on the protonated (H3app)3+ cation makes 5 sensitive to water and a hydrolysis reaction occurs to generate a cubic AgI phase. Finally, 1-3 exhibit high photocatalytic efficiencies for the degradation of rhodamine B (RhB) dye in wastewater under visible light. All conclusions obtained here will help a lot in the synthesis of stable functional metal halide-based hybrids.

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